Unique constraint on single String column with GreenDao2 - 屁屁侠

Unique constraint on single String column with GreenDao2

转：http://software.techassistbox.com/unique-constraint-on-single-string-column-with-greendao_384521.html

 

I want to make unique constraint on String value with GreenDao. I have following piece of code:

Entity category = schema.addEntity(\'Category\');
category.addIdProperty();
category.addStringProperty(\'Name\').notNull();

How can I make sure that Name will be unique?

My tries:

I have found methods PropertyBuilder.unique() and PropertyBuilder.index() but none of this works.

index() doesn\'t work at all and allows to make duplication. unique() throws exception in Robolectric test but don\'t do anything when app runs on device Robolectric exception:

android.database.sqlite.SQLiteException: Cannot execute for last inserted row ID, base error code: 19
    at org.robolectric.shadows.ShadowSQLiteConnection.rethrow(ShadowSQLiteConnection.java:48)
    at org.robolectric.shadows.ShadowSQLiteConnection.access$500(ShadowSQLiteConnection.java:26)
    at org.robolectric.shadows.ShadowSQLiteConnection$Connections.execute(ShadowSQLiteConnection.java:436)
    at org.robolectric.shadows.ShadowSQLiteConnection.nativeExecuteForLastInsertedRowId(ShadowSQLiteConnection.java:239)
    at android.database.sqlite.SQLiteConnection.nativeExecuteForLastInsertedRowId(SQLiteConnection.java)
    at android.database.sqlite.SQLiteConnection.executeForLastInsertedRowId(SQLiteConnection.java:782)
    at android.database.sqlite.SQLiteSession.executeForLastInsertedRowId(SQLiteSession.java:788)
    at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:86)
    at de.greenrobot.dao.AbstractDao.executeInsert(AbstractDao.java:348)
    at de.greenrobot.dao.AbstractDao.insert(AbstractDao.java:293)

So far I have made something like this but I don\'t think it\'s the best solution. 

However if this correct, is it good idea to add index() to name Property to get better performance?

 

public Long insert(Category category) {
    if (getByName(category.getName()) != null) {
        throw new DuplicateCategoryNameException(category.getName());
    }
    ...
}

public Category getByName(String name) {
    return categoryDao.queryBuilder().where(CategoryDao.Properties.Name.eq(name)).build().unique();
}